html {
    filter: progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);
    -webkit-filter: grayscale(100%);
}
#app {
    width: 50vh;
    height: 50vh;
    background-color: brown;
    display: flex;
    align-items: center;
    justify-content: center;
}

.span_style {
    color: cornflowerblue !important;
}